Starting fuel feed system for the fuel injection of an internal combustion engine

ABSTRACT

A very useful starting fuel feed system capable of easily and reliably starting an internal combustion engine, the system being so constructed that the temperature conditions of the internal combustion engine prior to its starting as represented by the temperature of the engine cylinder wall or the cooling water is detected by means of a thermistor or a cold conductor, and that, almost simultaneously only with the actuation of a starting switch or only at the instant a starting motor starts rotating, an electrical pulse is applied to each injection valve whose pulse duration is sufficient to satisfy the required quantity of fuel for starting the engine under the said detected temperature conditions.

United States Patent Omori [4 1 Aug. 1, 1972 [54] STARTING FUEL FEED SYSTEM FOR 3,311,102 3/1967 Voigt ..l23/l 79 L THE FUEL INJECTION OF AN 3,463,130 8/1969 Reichardt 123/32 INTERNAL COMBUSTION ENGINE 3,504,657 4/1970 Eichler 123/1 19 Inventor: Norio Omori, Kariya, Japan FOREIGN PATENTS OR APPLICATIONS [73] Assignee: Toyota Jidosha ogyo Kab k 1,156,103 12/1957 France ..123/179 L Kaisha, Toyota-shi, Japan Primary Examiner-Laurence M. Goodridge [22] Flled' 1970 Assistant Examiner-Ronald B. Cox [21] Appl. No.: 10,798 Attorney-Cushman, Darby & Cushman [30] Foreign Application Priority Data [57] ABSTRACT A very useful starting fuel feed system capable of easi- Feb. 15, 1969 Japan ..44/1 1401 y and reliably starting an intern a1 combustion g the system being so constructed that the temperature [52] "123/32 123/119 Egg/{1,236 conditions of the internal combustion engine prior to [51] Int Cl F02!) 3/00 F02 17/00 its starting as represented by the temperature of the [58] Fieid 123/32 engine cylinder wall or the cooling water is detected y means of a thermistor or a cold conductor, and that, almost simultaneously only with the actuation of [56] References Cited a starting switch or only at the instant a starting motor UNITED STATES PATENTS starts rotating, an electrical pulse is applied to each injection valve whose pulse duration is sufficient to 3,616,784 11/1971 Barr ..123/32 EA satisfy the required quantity of fuel f starting the g a gine under the said detected temperature conditions. e mi 3,032,025 5/1962 Long ..l23/l79 L 1 Claim, 3 Drawing Figures 5 301 FUEL p TANK v 6 PRESSUTFE P Q I A30 REGULA j 8 7 TEMPER ITUR J i ,1 I 057E670? 3 /4 /2 HOLD/N6 4 C/RCU/r T KEY SWITCH //VLE7' P/PE a ate 5d 0575mm /0 L ELECTRON/C CONTRG. U/V/ T STARTING FUEL FEED SYSTEM FOR THE FUEL INJECTION OF AN INTERNAL COMBUSTIO ENGINE The present invention relates to a fuel injection internal combustion engine and more particularly to a system adapted to feed the necessary amount of fuel to start, at a temperature below or slightly higher than C, a fuel injection internal combustion engine provided with an electronic control unit for controlling the valve opening time of electrically controlled injection valves mounted in an inlet pipe for the engine in accordance with the duration of an electrical pulse which satisfies the requirements of the engine.

With conventional fuel injection internal combustion engines of this type, the generally employed fuel injection system for starting the engine at low temperatures has consisted of a system wherein the temperature of the engine cylinder wall or the cooling water is detected and electrical pulses having a pulse duration proportional to the detected temperature are successively applied to injection valves from an electronic control unit to ensure the increased amount of fuel supply required for cold starting. For instance, the Volkswagen VW 1600 car, which is well known as one of the cars that has this kind of fuel injection internal combustion engine installed, employs the aforesaid fuel feed system in which the amount of fuel delivered is controlled by detecting the temperature of the cylinder wall of the engine.

Under these circumstances, the present inventor also conducted a research to develop a novel fuel feed system and obtained fairly good results in terms of good cold starting by developing a fuel feed system wherein the temperature of the engine cylinder wall or the cooling water is detected while a starting motor for the engine is running so that electrical pulses whose pulse duration corresponds to the detected temperature are successively applied to the injection valves from an electronic control unit.

However, subsequent research work proved that all of the previously mentioned systems still had the drawbacks will be discussed hereunder.

In other words, while there will be no problem if the air-fuel ratio is a combustible one under the existing temperature conditions and a proper spark is delivered from a spark plug and moreover the number of rotations of a starter motor is sufficient so that the starting operation may be completed in a very short period of time, there is a disadvantage in that, if at least any one of the said three requirements is not satisfied for some reason, the initial explosion or a complete explosion will fail to take place, resulting in a longer starting time, and although no combustion is taking place within the cylinders of the engine, the amount of fuel necessary to start the engine under said temperature conditions will be successively supplied to the engine while a starter motor is rotating, so that the unburnt fresh fuel will increase within the engine cylinders and moisten the spark plugs, thus making it harder to start the engine.

It is therefore the object of the present invention to provide a starting fuel feed system for an internal combustion engine comprising electrically controlled injection valves serving as fuel injection valves and an electronic control unit adapted to control the valve opening time of said injection valves by means of electrical pulses whose pulse duration is proportional to the number of revolutions or the load of the engine, characterized in that the temperature conditions of the engine prior to the starting thereof is detected by means of a temperature detector, and that, almost simultaneously only with the actuation of a starting switch or only at the instant a starting motor starts rotating, an electrical pulse having a pulse duration sufficient to satisfy the required quantity of fuel for starting the engine under said temperature conditions is applied to each injection valve.

According to the present invention, there is a remarkable effect in that, even if an engine fails to start and the starting motor continues to rotate with the starting switch being actuated, fuel will not be excessively supplied to the engine with the result that moistening of the spark plugs and the like may be prevented as far as possible and that the restarting of the engine may be readily effected, thereby ensuring easy and reliable starting.

Now the present invention will be explained in detail below in conjection with an embodiment of the invention illustrated in the accompanying drawings in which:

FIG. 1 is a block diagram showing a starting fuel feed system for a fuel injection internal combustion engine according to the present invention, and

FIG. 2 and FIG. 3 are graphs for explaining the action of the system according to the present invention.

Referring to FIG. 1, numeral 1 designates injection valves mounted in an inlet pipe 3 of an internal combustion engine 2 which are equal in number to the engine cylinders, and the valve 1 is a kind of solenoid valve whose opening time is electrically controlled. Numeral 4 designates a fuel tank; 5 a fuel pump; 6 a fuel distributor; 7 a pressure regulator for maintaining pressure in the fuel lines, which extend from the pump 5 to the pressure regulator 7 itself as well as to the injection valves 1, at a substantially constant pressure value. Numeral 8 designates an engine rpm detector to produce a pulse proportional to the number of revolutions of the engine 2; 9 an inlet pipe internal pressure detector mounted on the inlet pipe 3 of the engine 2. Numeral l0 designates an electronic control unit adapted to mainly receive at the input thereof the electrical outputs from the engine rpm detector 8 and the inlet pipe internal pressure detector 9 to apply to the respective injection valves 1 electrical pulses whose pulse duration is sufficient to supply the amount of fuel that meets the requirement of the engine 2 under such input conditions. Numeral 11 designates a temperature detector to detect the temperature of the engine 2, and in the present embodiment it is composed of a thermistor whose characteristic curve of resistance value R (in ohm) vs. temperature t C) is substantially as shown by a full line in FIG. 2, the detector 11 being mounted at a suitable position to detect the temperature of the engine 2 such as on the cylinder head portion or in the cooling water passages in the radiator. Numeral l2 designates a key switch for starting the engine and its function is to supply power from a power source which is not shown (usually a storage battery installed in a car) to the pump 5, electronic control unit 10, the starting motor which is not shown and a holding circuit 14 through electrical distributing wires 13a, 13b, 13c and 13d shown by the alternate long and two short dashes lines, thus operating these components. The holding circuit 14 is a circuit for producing an electrical pulse whose pulse duration is proportional to the resistance of the temperature detector 11 and it serves to apply an electrical pulse of a suitable duration to the respective injection valves 1 only once upon closure of the said key switch 12 and independently of those electrical pulses whose pulse duration is controlled by the electronic control unit 10 when the engine 2 is rotating.

With the arrangement described above, the operation of the system according to the present invention will now be explained. In starting the engine under cer tain temperature conditions, closing of the key switch 12 supplies power to the respective component units of the system from the power source through the distributing wires 13a, 13b, 13c and 13d, whereupon the pump 5 rotates and the electronic control unit operates so that the starting motor rotates and the holding circuit 14 is actuated. The holding circuit 14 applies an electrical pulse whose pulse duration is proportional to the resistance value of the temperature detector 11 which detects the temperature of the engine 2, to each injection valve 1 through the electronic control unit 10. Thus, the necessary amount of fuel to start the engine 2 may be reliably fed to the engine. Of course, the timing at which an electrical pulse is applied to each injection valve 1 from the holding circuit 14 through the electronic control unit 10 may be selected to coincide with the timing of the starting motor to start rotation. It is important to ensure that, in starting the engine, an electrical pulse having a suitable duration to feed the necessary amount of fuel for starting the engine is applied only once to each of the injection valves 1 when the key switch 12 is closed. Then, once the engine is started, the electronic control unit 10 applies to each injection valve 1 electrical pulses having a pulse duration which supplies the necessary amount of fuel to maintain the continued smooth operation of the engine under the existing temperature conditions thereof. If the engine fails to start in the said manner, the key switch 12 may be actuated again so that an electrical pulse will be reapplied to each of the injection valves 1 from the holding circuit 14 through the electronic control unit 10.

FIG. 3 shows a pulse duration characteristic of an electrical pulse applied to each of the injection valves from the holding circuit 14 when a good starting characteristic is attained by the system of the present invention in an internal combustion engine whose displacement is 2,000 cc. In FIG. 3, the vertical coordinate represents the pulse duration T (msec.) of the electrical pulse and the horizontal coordinate represents the temperature t C) of the engine cylinder head.

Moreover, in order to ensure good starting characteristic of equal effectiveness, instead of applying to each injection valve a single electrical pulse having a long duration as described above, two or three electrical pulses each having a duration which is one half or one third of the pulse duration of the said single pulse may be successively applied to each injection valve in a split mode, and it is apparent that this is also covered by the concept of the present invention.

What is claimed is:

l. A starting fuel feed system for an internal combustion engine having an engine starting motor, come l rically controlled fuel injection valves for said engine,

means including an electronic control unit connected to said valves for delivering thereto during engine running time electrical pulses whose pulse duration is responsive to the number of engine revolutions and load,

means for detecting the temperature of said engine before each start of said starting motor,

means connected between said temperature detecting means and said electrical pulse delivering means for causing the latter to pulse the said valves substantially concurrently to effect fuel injection during only the starting pulse duration required by the said detected temperature to the exclusion of other engine parameters, and

means for automatically causing said starting pulse duration to occur only once for each start of said starting motor regardless of how long that motor is operated and to start substantially at the time that motor starts for satisfying the quantity of fuel required to start the said engine at the detected I temperature. 

1. A starting fuel feed system for an internal combustion engine having an engine starting motor, comprising: electrically controlled fuel injection valves for said engine, means including an electronic control unit connected to said valves for delivering thereto during engine running time electrical pulses whose pulse duration is responsive to the number of engine revolutions and load, means for detecting the temperature of said engine before each start of said starting motor, means connected between said temperature detecting means and said electrical pulse delivering means for causing the latter to pulse the said valves substantially concurrently to effect fuel injection during only the starting pulse duration required by the said detected temperature to the exclusion of other engine parameters, and means for automatically causing said starting pulse duration to occur only once for each start of said starting motor regardless of how long that motor is operated and to start substantially at the time that motor starts for satisfying the quantity of fuel required to start the said engine at the detected temperature. 